Convert old flexbox uses in html.css to new flexbox (non-<select>)
https://bugs.webkit.org/show_bug.cgi?id=110837

Patch by Christian Biesinger <cbiesinger@chromium.org> on 2013-03-18
Reviewed by Ojan Vafai.

No new tests (No change in behaviour)

* css/html.css:
(input::-webkit-clear-button):
Missed this one in the original patch.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146103 268f45cc-cd09-0410-ab3c-d52691b4dbfc